<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // undefind
        // var x;
        // alert(x)
        //字符
        var str1 ="hello world";
        var str2 ="hello world";
        console.log(str1)
        console.log(str2)
        //var str3 ="hello world";
        var str4 ="懒羊羊说：‘去他妈的灰太狼，老子可是懒大王’";
        console.log(str4);
        var str ="Java";
        //JS中先运算等号右边的语句
        str = str+"script";
        console.log(str)
    </script>
</body>
</html>